I need help with breaking a object
Use the Cell Fracture add-on, it's the most common way to break stuff in Blender. 

Once you've enabled it, click your object, press the spacebar and search "Cell Fracture". 

It may change your object into something like this, depending on the settings you use for the fracturing.(if you can't see your fractured object, look at the next layer) 

The fun part begins: select all the fractures and turn them all into Rigid Bodies, and check the "Animated". (make sure all of the fractures have the "Animated" checked, or else the whole thing will fall apart without collision)

Once you've set up your hammer or anything that breaks your object, make sure that is a Rigid Body too, with the "Animated" box checked. 

Animate your colliding object through your breaking object, then you animate the "Animate" checkbox. If you don't know how to do that, just hover your mouse over the "Animated" checkbox and click I. Then go the the keyframe where your colliding object is just about to collide with your breaking object, then click I again. Go to the next keyframe, uncheck the "Animated" box and press I again. Now it works! 

Do the same thing with your breaking object, but make sure it is well timed, because your breaking object might get destroyed before the impact. Now have fun and amuse yourself with your destroying things!